Various methods for measuring a cross-sectional shape by scanning electron microscope (SEM) viewing have been proposed as methods for determining the quality of a pattern formed on the surface of a semiconductor wafer. Measurement of a cross-sectional shape by SEM is performed by a method in which an electron beam radiated to a pattern on the tested substrate is scanned in the cross-sectional direction of the pattern, reflected electrons or secondary electrons from the pattern are detected and analyzed, and the cross-sectional shape of the scanned portion is calculated. The operation described above is performed at several points on the pattern to determine the quality of the shape of the entire pattern.
In measurement by SEM as described above, the operation of radiating and scanning an electron beam on the pattern is repeated several times, and a long time is therefore required to calculate the shape of the pattern. Since the viewing magnification is also high, the pattern shape for the entire wafer is difficult to calculate, and the quality of the entire wafer is determined by sampling several points. As a result, flaws in portions of the pattern other than those sampled are overlooked. In a resist pattern, when an electron beam is radiated, the electron beam is absorbed by the resist according to the acceleration voltage, and the pattern becomes charged and eroded. In some cases, discharge occurs and the pattern collapses, and because of inconvenience in subsequent steps, the optimum viewing conditions are also calculated while various modifications are made to the acceleration voltage or the viewing magnification. Measurement therefore requires even more time.
In order to overcome such problems, a surface inspection device and surface inspection method have been proposed whereby the quality of a pattern shape on a tested substrate can be distinguished in a short time regardless of whether the pattern is a resist pattern or an etched pattern (see Japanese Laid-open Patent Publication No. 2006-135211, for example).